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Variable-magnification projection optical system and projection display device

a projection optical system and variable magnification technology, applied in the field of variable magnification projection projection optical system and projection display device, can solve the problems of low zoom ratio of the zoom lens of patent document 2, short back focus and low zoom ratio, etc., to minimize the size increase of the entire system, high zoom ratio, and high versatility

Active Publication Date: 2014-04-24
FUJIFILM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention aims to provide a variable-magnification projection optical system that can easily achieve a wide-angle projection optical system, while keeping the outer diameters of the enlargement side lenses in check, and providing a good projection image. The system should be telecentric on the reduction side, have a long back focus and high zoom ratio, and avoid excessive increase in the outer diameters of the enlargement side lenses. The technical effects of the invention would therefore be the achievement of a versatile optical system with high-quality projection images.

Problems solved by technology

However, the projection zoom lens of Patent Document 1 has drawbacks that it has a short back focus and a low zoom ratio.
The projection zoom lens of Patent Document 2 has a drawback that it has a low zoom ratio.
The projection zoom lens of Patent Document 3 has a drawback that it has a short back focus.

Method used

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  • Variable-magnification projection optical system and projection display device

Examples

Experimental program
Comparison scheme
Effect test

example 2

[0115]FIGS. 3 and 4 show the lens configuration and ray trajectories at the wide-angle end of the variable-magnification projection optical system of Example 2, and positions of the lens groups and ray trajectories in different magnification positions of the variable-magnification projection optical system of Example 2, respectively. The configuration of the variable-magnification projection optical system according to Example 2 is substantially the same as that of the variable-magnification projection optical system according to Example 1, except that the fifth lens L5 of the first lens group G1 is formed by a biconvex lens, and the seventh lens L7 of the second lens group G2 is formed by a positive meniscus lens with the convex surface facing the reduction side.

[0116]The f-number “Fno.” and the total angle of view “2ω” of the variable-magnification projection optical system of Example 2 are shown above Table 2, the basic lens data is shown in the upper table of Table 2, and the va...

example 3

[0117]FIGS. 5 and 6 show the lens configuration and ray trajectories at the wide-angle end of the variable-magnification projection optical system of Example 3, and positions of the lens groups and ray trajectories in different magnification positions of the variable-magnification projection optical system of Example 3, respectively. The configuration of the variable-magnification projection optical system according to Example 3 is substantially the same as that of the variable-magnification projection optical system according to Example 1, except that the fifth lens L5 of the first lens group G1 is formed by a biconvex lens, and the seventh lens L7 of the second lens group G2 is formed by a positive meniscus lens with the convex surface facing the reduction side.

[0118]The f-number “Fno.” and the total angle of view “2ω” of the variable-magnification projection optical system of Example 3 are shown above Table 3, the basic lens data is shown in the upper table of Table 3, and the va...

example 4

[0119]FIGS. 7 and 8 show the lens configuration and ray trajectories at the wide-angle end of the variable-magnification projection optical system of Example 4, and positions of the lens groups and ray trajectories in different magnification positions of the variable-magnification projection optical system of Example 4, respectively. The symbol (positive or negative) of the refractive power of each of the first to the fifth lens groups G1 to G5, the lens groups that are fixed during magnification change, and the lens groups that are moved during magnification change of the variable-magnification projection optical system according to Example 4 are the same as those of the variable-magnification projection optical system according to Example 1. The variable-magnification projection optical system of Example 4 differs from the variable-magnification projection optical system of Example 1 in that the lens groups of the variable-magnification projection optical system of Example 4 have ...

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PUM

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Abstract

A variable-magnification projection optical system substantially consists of a negative first lens group that is disposed at the most enlargement-side position and is fixed during magnification change, a positive last lens group that is disposed at the most reduction-side position and is fixed during magnification change, and a plurality of lens groups that are disposed between the first lens group and last lens group and are moved during magnification change. The lens groups that are moved during magnification change substantially consist of three lens groups, wherein the most enlargement-side lens group is a negative lens group. Predetermined conditional expressions relating to a back focus of the entire system on the reduction side at the wide-angle end, a focal length of the entire system at the wide-angle end, a focal length of the last lens group, and a focal length of the first lens group are satisfied.

Description

TECHNICAL FIELD[0001]The present invention relates to a variable-magnification projection optical system and a projection display device. In particular, the present invention relates to a variable-magnification projection optical system that is suitable for projection on a large screen at movie theaters, etc., and a projection display device employing the variable-magnification projection optical system.BACKGROUND ART[0002]Conventionally, projector devices (projection display devices) using a light valve, such as a liquid crystal display element or DMD (Digital Micromirror Device®), are widely used. Further, in recent years, projection display devices of the above-described type which are capable of projecting a higher definition image and applicable to a large screen are being used at movie theaters, etc. A projection display device for use in this manner employs a three-chip system, wherein three light valves for individual primary colors are provided, a bundle of rays from a ligh...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G02B15/14
CPCG02B15/14G02B15/177G02B15/145529
Inventor NAGATOSHI, YUKIKONAGAHARA, AKIKO
Owner FUJIFILM CORP
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